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ProbabilitySampler.java
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ProbabilitySampler.java
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.htrace.core;
import java.util.concurrent.ThreadLocalRandom;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Sampler that returns true a certain percentage of the time. Specify the frequency interval by
* configuring a {@code double} value for {@link #SAMPLER_FRACTION_CONF_KEY}.
*/
public class ProbabilitySampler extends Sampler {
private static final Log LOG = LogFactory.getLog(ProbabilitySampler.class);
public final double threshold;
public final static String SAMPLER_FRACTION_CONF_KEY = "sampler.fraction";
public ProbabilitySampler(HTraceConfiguration conf) {
this.threshold = Double.parseDouble(conf.get(SAMPLER_FRACTION_CONF_KEY));
if (LOG.isTraceEnabled()) {
LOG.trace("Created new ProbabilitySampler with threshold = " +
threshold + ".");
}
}
@Override
public boolean next() {
return ThreadLocalRandom.current().nextDouble() < threshold;
}
}